1. Field of the Invention
The present invention relates to an image formation device and an image formation method. More specifically, the invention relates to an image formation device that transfers toner images formed with toners of multiple colors onto a recording medium, such as paper, so as to form a color image, and a corresponding image formation method.
2. Description of the Prior Art
As is known in the art, a conventional image formation device that is capable of forming a color image, such as a color laser printer or a color photocopier, develops electrostatic latent images of respective colors formed on a photoreceptor as toner images with toners of respective colors, transfers the toner images of the respective colors in an overlapping manner as a composite color toner image on an intermediate transfer medium, such as a transfer belt, and transfers and fixes the composite color toner image as a resulting color image on a recording medium like paper. The toner density of each toner image formed on the photoreceptor or the intermediate transfer medium is varied with a variation in working environment, for example, the temperature or the humidity. The image formation device accordingly carries out adjustment of a toner image formation process according to the working environment.
A variation in toner density of the toner image less affects the picture quality of a resulting monochromatic image, compared with that of a resulting color image. The prior art image formation device, however, adopts the same procedure for adjustment of the toner image formation process in the case of formation of a monochromatic image and in the case of formation of a color image. Such adjustment applies unnecessary, excessive loads onto the respective constituents of the image formation device and thereby accelerates deterioration of the constituents.